Line items on a Sales Order should be flagged as Drop Shipped. When invoiced, they will not reduce Qty on Hand. Likewise, the PO should be a Drop Ship type which will not increase the QOH. With a D/S PO, you skip the Receipt of Goods and just do a Receipt of Invoice. The S/O Invoice will post to the revenue. The P/O invoice will post to the COGS. Nothing will impact Inventory GL since it is not coming in or going out of that account.